The invention relates to pressed or compressed chloramine-T tablets and a method for the production thereof. Chloramine-T is a known disinfecting and antistaling agent, which is usable in wide ranges of application. It is normally in the pulverulent state, where it is difficult to handle. This is in part due to the fact that the powder easily flies up during handling. It is therefore desirable to have chloramine-T in a compact form, particularly in a tablet form. Tablets containing chloramine-T are already known. These tablets are used for keeping cut flowers fresh, in that they are added to the water for the flowers. However, the tablets have an active ingredient content below 20 wt. %.
For the industrial use of chloramine-T, particularly in the hygiene sector, food production and disinfection, not only are larger chloramine-T quantities necessary, but also higher chloramine-T active ingredient contents are desired, namely for cost reasons, transportation reasons and for avoiding larger quantities of auxiliary agents or adjuvants, which have no effect and are prejudicial during use or can give rise to disposal problems. However, without larger quantities of pressing or compressing agents, it is not possible to press or compress pulverulent chloramine-T with an adequate strength.
The problem of the invention is therefore to provide chloramine-T tablets with a high active ingredient content and correspondingly low quantities of pressing agents and other additives. The tablets are to have an adequate strength for handling, associated with a rapid dissolvability.
The compressed tablets according to the invention contain more than 50 wt. % of chloramine-T as the main constituent, as well as at least one pressing agent and at least one agent aiding rapid dissolving, particularly a disintegrating agent, as secondary constituents. Apart from pressing agents and solubilizers or disintegrating agents, if desired, further secondary constituents may be present, particularly fillers or also other adjuvants or auxiliary agents, such as antifoaming agents. The chloramine-T active ingredient content is preferably at least 80 wt. %, particularly at least 90 wt. %. In special cases it can even be up to 97 wt. %. Such high active ingredient contents are made possible through the combination of pressing agents and solubilizers.
Preferably at least one of the secondary constituents has combined characteristics and serves both as a pressing agent and as a solubilizer. In this way it is possible to keep the content of secondary constituents low and to correspondingly raise the active ingredient content. As pressing agents are in particular suitable magnesium stearate, highly disperse amorphous silica (silicon dioxide), pulverulent polyethylene glycols, sodium carboxymethyl cellulose and/or microcrystalline cellulose.
As agents aiding rapid dissolving, particularly as disintegrating agents, are in particular suitable sodium carboxymethyl starch or sodium-starch-glycolate, prepasted corn starch, sodium carboxymethyl cellulose and/or pulverulent polyethylene glycols. These constituents are more particularly suitable because even in small proportional quantities of 0.25 to less than 5 wt. %, particularly in combination with one another, they evolve their full efficacy. The mixture preferably contains at least approximately 60%, particularly at least approximately 80% of the aforementioned substances.
Chloramine-T ((N-chloro-p-toluenesulphonamido) sodium) has a very broad action spectrum as a disinfectant. It is active against bacteria, viruses, yeasts, fungi and algae, so that there is a very wide application spectrum. Great significance is attached here to the hygiene sector, particularly in clinics, public baths abattoirs, etc. It is a valuable disinfectant in agriculture and in veterinary medicine. It is suitable for conserving water, particularly for keeping fountains clean. According to the invention the tablets have an active ingredient content of chloramine-T of more than 50 wt. %. In fact, higher active ingredient percentages are possible and desired. Thus, as a rule, the active ingredient proportion is at least 70 wt. % or higher. Tablets with a high chloramine-T content have an active ingredient content of 80 or 90 wt. %. The weight proportion of auxiliary substances is correspondingly low and substantially and generally make up the difference to 100%. However, it has been found that a larger number of auxiliary substances, which exercise a mutual, synergistic effect, is more favourable than a higher weight proportion of only a few auxiliary substances.
Preferred embodiments contain as auxiliary substances or secondary constituents several or most of the following substances:
a) Highly disperse amorphous silicon dioxide (silica). This is used as a pressing aid and lubricant. It is generally present in quantities of 0.25 to 2 wt. %, particularly 0.5 to 1 wt. %.
b) Sodium carboxymethyl cellulose. This can be present in the form of different types, particularly with a degree of substitution of 0.75 to 0.8. Sodium carboxymethyl cellulose acts both as a binder and as a solubilizer (disintegrating agent). It is generally present in quantities of 1 to 3 wt. %, particularly 1.5 to 2 wt. %.
c) Sodium carboxymethyl starch and/or sodium-starch-glycolate. The latter is in particular an excellent disintegrating agent. The quantities are generally 0.5 to 4 wt. %, particularly 1 to 2.5 wt. %. Croscarmellose (AVEBE) is also suitable as a disintegrating agent.
d) Corn starch, particularly prepasted corn starch. The latter serves as a disintegrating agent and cooperates in an excellent manner with sodium carboxymethyl starch and in particular sodium-starch-glycolate. The quantities are generally 0.5 to 10 wt. %, particularly 1 to 3 wt. %.
e) High purity microcrystalline cellulose. The latter has the function of a filler or binder and aids a homogeneous mixing during the mixing of the individual constituents. The quantities are generally 0.5 to 10 wt. %, particularly 1 to 3 wt. %.
f) Polyethylene glycols. These are generally present in the mixture as pulverulent solids. They have binder characteristics for the tablet, but also aid dissolving. The quantities are generally 1 to 5 wt. %, particularly 2 to 3 wt. %.
g) Gum Arabic. The latter serves as a binder and can in particular also be used in place of polyethylene glycols. The quantities are generally 0.5 to 5 wt. %, particularly 1 to 3 wt. %.
h) Magnesium stearate. This is a known pressing agent, which allows the tablet to have smooth surfaces and serves as a lubricant for the punch.
i) Sodium chloride (common salt). This is used for the electrochemical stabilization of chloramine-T at higher temperatures and under non-optimum storage conditions. The quantities are generally 1 to 5 wt. %, particularly 2 to 3 wt. %.
Apart from these constituents, for special application purposes further constituents can be present, such as e.g. antifoaming agents in water treatment and the like. Surfactants or detergents, together with dyes and perfumes can also be present. Stabilizing agents can also be used for ensuring storage stability and activity under extreme environmental conditions. These further constituents for special applications are added to the 100% of the aforementioned constituents. Surfactants can be present in quantities of 0.5 to 30 wt. %, particularly 0.5 to 2 wt. %, stabilizers in quantities of 0.5 to 20 wt. %, particularly 0.5 to 3 wt. %, dyes or perfumes in quantities of 0.5 to 20 wt. %, particularly 0.5 to 2 wt. % additionally to the 100%. Approximately 1 to 5 wt. % are sufficient for antifoaming agents. Generally the total quantity of the further constituents together is less than 10 wt. %. If the further constituents also have characteristics as pressing agents or solubilizers, the quantity of the aforementioned pressing agents and solubilizers can be reduced. The individual constituents can also be replaced by others having an equivalent action.
In particularly preferred embodiments of the invention there are at least 4, particularly at least 6 of the aforementioned auxiliary substances present as secondary constituents in the tablet. The secondary constituents are either water-soluble, which is preferred, or are present in such a finely divided form or are obtained in such a finely divided form when the tablets disintegrate, that the complete tablet substantially forms a clear solution. Chloramine-T is in any case adequately water-soluble.
In a preferred embodiment the tablets are constructed as dosing tablets. For this purpose the tablet size is preferably adjusted in such a way that with predetermined, easily measurable liquid volumes it is possible to obtain solutions with a predetermined chloramine-T concentration. Chloramine-T is active in concentrations of 0.001 to 15 wt. % and normally solutions with a concentration of 5% or less are adequate. Preferably use is made of solutions with a chloramine-T active ingredient content of approximately 0.5 wt. %. Preference is therefore given to tablet sizes or dosing tablets with which in simple manner such active ingredient solutions can be prepared. For practical handling for example two tablet sizes are adequate, particularly one tablet size with an active ingredient content of 2.5 g of chloramine-T. If this tablet is dissolved in half litre of water, then an active ingredient solution is obtained with 0.5 wt. % chloramine-T. The other tablet size contains 50 g of chloramine-T. When dissolved in 10 litres of water once again active ingredient solutions of 0.5 wt. % chloramine-T are obtained. Larger tablets, particularly with a diameter of 20 mm or more are generally called tabs. The term tablets also covers larger pressed or compressed articles. Generally they have a cylindrical, particularly a flat cylindrical shape. However, the tablets can also have some other geometrical shape, e.g. a cubic or spherical construction. Preference is given to tablet shapes with a maximum large surface/weight, because this makes it possible to achieve very rapid dissolving rates. The tablet hardness is preferably so adjusted through the choice of the auxiliary agents and pressing conditions, that the tablets can still be broken by hand and as a result the rapid dissolving is also assisted. During pressing or compressing, it is also possible to impress preset breaking points. Even with larger tablets dissolving is possible within a period of less than one minute, particularly less than 45 seconds, dissolving preferably taking place accompanied by stirring. Dissolving can be carried out at ambient temperature. Heating is not necessary.
Chloramine-T is biogradable. Preferably the secondary constituents are selected in such a way that all the constituents are at least biologically unobjectionable. In particular, at least the main quantity of the secondary constituents is biogradable or compostable. This is the case with the aforementioned constituents. Particularly when used in hygiene and medicine, as well as for drinking water treatment, all the constituents should be present at least in DAB-10 quality, i.e. having the purity intended for pharmaceuticals. The tablets according to the invention advantageously have a smooth, closed surface, without being provided with a coating. This permits dustless handling. The density of the tablets is preferably in the range 1.0 to 1.3 g/cm3 and in particular at approximately 1.1 g/cm3. The tablets can have a per se known impression, which, in particular gives details on the active ingredient, the active ingredient quantity and/or the liquid volume used. It is also possible to impress a trademark. The impressions can be combined with the aforementioned preset breaking markings.
Preferably the tablets are placed in a pack, where the tablets are individually packed. This pack is in particular moisture-tight and airtight. As a result the tablets can be stored for a very long time and are insensitive to external influences. Soda kraft paper, which has a PE (polyethylene) coating is particularly suitable for packing purposes. This coating serves as a moisture barrier and simultaneously as a heat seal coating during packing. This coating is so thin that, following removal of the tablet, the packing is completely biodegradable, so that no special disposal is required.
The invention also relates to a method for producing the tablets according to the invention. In this method all the starting substances are premixed dry in pulverulent form, particularly in a very finely powdered form. The mixture is filled into a tablet press and compressed to tablets. Intermediate storage can take place between mixing and compression, because demixing need not be feared. Pressing can take place at pressures of 50 to 300 N/mm2, particularly at 100 to 250 N/mm2. For a tablet with an active ingredient content of 2.5 g of chloramine-T and a diameter of 20 mm this corresponds to a pressing pressure of 4 to 8 t and with a tablet having 50 g of solids and a diameter of 50 mm this corresponds to a pressing pressure of approximately 20 t up to 24 t. At these pressures tablets with a strength adequate for handling are obtained, but which, if desired, can still be broken with the hand.